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Old 27-10-2009, 18:08   #1
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R12 to R134a

  • What it is it going to take to switch my cold plate to R134 its been sitting for awhile Everything seems to work except for the refridgerant No pressure in the lines. thanks everyone.

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Old 27-10-2009, 18:13   #2

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Refrigerant doesn't wear out so first thing to do is find all the leaks. Then we can discuss what to do next.

Personally I recommend against conversions in areas where highest efficiency is a prerequisite. It is very unlikely the machine will work as well on 134 vs 12.

Your mileage may vary.

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Old 31-10-2009, 05:37   #3
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A word of warning, from Richard Kohlmann - Do not convert any hermetic compressors to 134a unless they are designed for 134a.

The new 134a refrigerant is not as efficient as R

KollmannMarine Boat Refrigeration Specialist

The older Danfoss BD 2.5 compressors use Freon R12 refrigerant and mineral refrigerant oil. Refrigerant 134a was not approved for these compressors because of its inability to mix with mineral oil and to change the oil to a compatible oil might destroy the insulation on the motor wiring.
There is one blended refrigerant, 409a, that can be used as a
replacement for R12 in BD2.5 compressors, but only in an emergency in cool climates. Warning, never mix refrigerants and always vacuum out the old before inserting a substitute.

Hermetically sealed compressors that are powered by alternating
current 110 or 220 volt may be filled with Alkylbenzene oil which is compatible with HCFC component refrigerants. Blended refrigerant 409a is recommended as a replacement for R12 in systems where the compressor contains alylbenzene oil.

Externally driven compressors, engine driven or those with large 12/24 volt motors are being converted from Freon R12 to 134a refrigerant. This also includes changing to a compatible Poly Ester conversion oil.

If you have one of these systems, contact the system manufacturer for their correct procedures for making this conversion.
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"

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Old 31-10-2009, 11:43   #4

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Hence the reason to find all the leaks. If has sat flat for some time will have moisture and air in the system which causes lots other problems. If for example the leak is in the line set where rubbed against something perhaps with multiple deep vacuum and filter/drier changes it may be resurrected and while R-12 is expensive it may be the most cost effective way to solve the problem. Amazingly enough I can't begin to tell you how many times I have found a machine low or empty of refrigerant only to find previous "technician" couldn't be bothered to secure all service valve caps/bonnets and the refrigerant was lost due to poor work habits.

Please before anyone wants to chastise me for suggesting the use of R-12 consider first the environmental costs of manufacturing a new system to use R-134. The copper mine, the petrochemicals used, electricity. etc. R-12 available in the US is recycled so none new is made - here at least - lots made and used in "developing" countries.
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